Declezville is a formerly unincorporated community in southwestern San Bernardino County, in the Inland Empire region of southern California.

[2] The community is named for William Declez, a naturalized U.S. citizen, born in France, well known for his marble business on Los Angeles Street.

Declez opened granite quarries in Southern California in the 1860s in the Jurupa Hills on Pyrite Street, and built several Mexican public buildings.

When the Southern Pacific Railroad built a spur to the large granite quarries, it named the junction Declez and the terminal Declezville, after the granite works owner.

[3] The community is located in the northwestern foothills of the Jurupa Mountains, and at the southeastern edge of the Pomona Valley.